In a calendar display device for displaying a date, a day and so forth in a wristwatch or the like, there are constructed a drive wheel to which a driving force is transmitted from a step motor or the like in a drive section, a follower wheel formed in a display section for effecting display with a date indicator, a day indicator and so forth, and a displaying transmission wheel for intermittently transmitting the rotation of the drive wheel to the follower wheel. For example, in a calendar display device shown in FIG. 17, a displaying transmission member 104 including two kinds of pawls 102, 103 is constructed with respect to a drive wheel 101 which rotates once in 24 hours, and once in 24 hours, one pawl 103 is meshed with an internal tooth 106 of a date indicator 105 (follower wheel) to rotate the date indicator 105 by one step. In addition, once in 24 hours, the other pawl 102 is meshed with an external tooth 108 of a day indicator 107 to rotate the day indicator 107 by one step. In addition, in the calendar display device, there are constructed a first display-correcting transmission wheel 113 by which a winding operation to a crown (not shown) is transmitted through a sliding pinion 112 of a winding stem 111, and a second display-correcting transmission wheel 114 which shifts to a position where it is internally meshed with the date indicator 105 when the winding stem 111 is pulled out by one step to rotate the crown in a correction direction for a date display. Therefore, it is possible to rapid-feed manually the date indicator 105 without the aid of the drive wheel 101 and the displaying transmission wheel 104. In addition, if the winding stem is pulled out by one step to rotate the crown in a correction direction for a day display (a direction opposite to the correction direction for the date display), the second display-correcting transmission wheel 114 is externally meshed with a third display-correcting transmission wheel 115 which is externally meshed with the day indicator 107, so that it is also possible to rapid-feed manually the day indicator 107.
In the thus constructed calendar display device, since the mesh between the pawls 102, 103 and the date indicator 105 and the day indicator 107 is released each time the displaying transmission wheel 104 finishes driving the date indicator 105 and the day indicator 107 by one step, if an external force is applied to a wristwatch, a phenomenon in which the date indicator 105 and the day indicator 107 freely rotate, a so-called display jumping, may occur. Thus, to the calendar display device, a mechanism for positioning the date indicator 105 and the day indicator 107 is imparted. For example, in the example shown in FIG. 17, a sheet-like jumper 121 is arranged with respect to the date indicator 105, and a top part 122 of the jumper 121 is engaged with the internal tooth 106 of the date indicator 105, as shown by the solid line L11, whereby the date indicator 105 is positioned and the display jumping of the date indicator 105 is prevented. Similarly, a sheet-like jumper 126 is provided with respect to the day indicator 107, and a top part 127 of the jumper 126 is engaged with the external tooth 108 of the day indicator 107, as shown by the solid line L12, whereby the day indicator 107 is positioned and the display jumping of the day indicator 107 is prevented.
Moreover, such a mechanism for preventing the display jumping of the date indicator and the day indicator, one making use of a lever and a cam, one making use of a Geneva mechanism, and one combining the Geneva mechanism and a jumper spring are disclosed in Japanese Unexamined Patent Publication Nos. 50-142265, 54-85756 and 52-134471, respectively.
However, in the conventional device making use of a jumper mechanism (see FIG. 17.), the top parts 122, 127 of the jumpers 121, 126 should rise above the internal tooth 106 of the date indicator 105 or the external tooth 108 of the day indicator 107 each time the date indicator 105 and the day indicator 107 are rotated by one step, as shown by the two-dot chain lines L13, L14 in FIG. 17, so that a force for deforming the jumpers 121, 126 is required. Therefore, there is a problem of a heavy load during the date feeding and the day feeding. Since such a load causes an increase in power consumption, the wristwatch requires an increase in size of a battery, thereby preventing a reduction in thickness of the wristwatch. In addition, when a power generation device making use of an oscillating weight or the like is contained in the wristwatch, the increased power required to deform jumpers 121, 126 requires a large-sized power generation device having high capability of power generation to accommodate the large power consumption, thereby preventing the reduction in thickness of the wristwatch.
On the other hand, in the device making use of a lever and a cam as disclosed in Japanese Unexamined Patent Publication No. 50-142265, it is difficult to properly set a timing of lifting the lever. In addition, in the device making use of the Geneva mechanism as disclosed in Japanese Unexamined Patent Publication No. 54-85765, the date feeding time is long, thus causing a slippage of date. Further, in the device disclosed in Japanese Unexamined Patent Publication No. 52-134471, there is a problem that jumping and slippage of date occur, and a heavy load for lifting a spring is required.
In consideration of the foregoing problems, an object of the present invention is to provide a display device in which the feeding operation load is light and display jumping does not occur, and a watch including the same.
In addition, an object of the present invention is to provide a display device which is also capable of correcting the display by rapid-feeding a displaying follower wheel, and a watch including the same.